From 4fce3729340f3fdd092e02646b38fa2126c0d200 Mon Sep 17 00:00:00 2001 From: Niklas Schnelle Date: Thu, 12 Jun 2025 19:43:03 +0200 Subject: [PATCH] s390/pci: Fix potential double remove of hotplug slot BugLink: https://bugs.launchpad.net/bugs/2114174 In commit 6ee600bfbe0f ("s390/pci: remove hotplug slot when releasing the device") the zpci_exit_slot() was moved from zpci_device_reserved() to zpci_release_device() with the intention of keeping the hotplug slot around until the device is actually removed. Now zpci_release_device() is only called once all references are dropped. Since the zPCI subsystem only drops its reference once the device is in the reserved state it follows that zpci_release_device() must only deal with devices in the reserved state. Despite that it contains code to tear down from both configured and standby state. For the standby case this already includes the removal of the hotplug slot so would cause a double removal if a device was ever removed in either configured or standby state. Instead of causing a potential double removal in a case that should never happen explicitly WARN_ON() if a device in non-reserved state is released and get rid of the dead code cases. Fixes: 6ee600bfbe0f ("s390/pci: remove hotplug slot when releasing the device") Reviewed-by: Matthew Rosato Reviewed-by: Gerd Bayer Tested-by: Gerd Bayer Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens (cherry picked from commit c4a585e952ca403a370586d3f16e8331a7564901) CVE-2024-56699 Signed-off-by: Massimiliano Pellizzer Acked-by: Edoardo Canepa Acked-by: Manuel Diewald Acked-by: Mehmet Basaran Signed-off-by: Mehmet Basaran --- arch/s390/pci/pci.c | 34 +++++++++------------------------- 1 file changed, 9 insertions(+), 25 deletions(-) diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c index cc0087a4c1a3..7b5017221408 100644 --- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -947,10 +947,8 @@ void zpci_device_reserved(struct zpci_dev *zdev) void zpci_release_device(struct kref *kref) { struct zpci_dev *zdev = container_of(kref, struct zpci_dev, kref); - int ret; - if (zdev->has_hp_slot) - zpci_exit_slot(zdev); + WARN_ON(zdev->state != ZPCI_FN_STATE_RESERVED); if (zdev->zbus->bus) zpci_bus_remove_device(zdev, false); @@ -958,28 +956,14 @@ void zpci_release_device(struct kref *kref) if (zdev_enabled(zdev)) zpci_disable_device(zdev); - switch (zdev->state) { - case ZPCI_FN_STATE_CONFIGURED: - ret = sclp_pci_deconfigure(zdev->fid); - zpci_dbg(3, "deconf fid:%x, rc:%d\n", zdev->fid, ret); - fallthrough; - case ZPCI_FN_STATE_STANDBY: - if (zdev->has_hp_slot) - zpci_exit_slot(zdev); - spin_lock(&zpci_list_lock); - list_del(&zdev->entry); - spin_unlock(&zpci_list_lock); - zpci_dbg(3, "rsv fid:%x\n", zdev->fid); - fallthrough; - case ZPCI_FN_STATE_RESERVED: - if (zdev->has_resources) - zpci_cleanup_bus_resources(zdev); - zpci_bus_device_unregister(zdev); - zpci_destroy_iommu(zdev); - fallthrough; - default: - break; - } + if (zdev->has_hp_slot) + zpci_exit_slot(zdev); + + if (zdev->has_resources) + zpci_cleanup_bus_resources(zdev); + + zpci_bus_device_unregister(zdev); + zpci_destroy_iommu(zdev); zpci_dbg(3, "rem fid:%x\n", zdev->fid); kfree_rcu(zdev, rcu); }